With numbers of feral hogs on the rise, the Missouri Department of Conservation is gearing up to eradicate the destructive pests on its areas. Agency officials say they hope to lead the way in developing policies and techniques to reduce threats to human and veterinary health and to the state's economic and ecological well-being.
Feral hogs -- free-ranging swine without owners -- have been present in Missouri since settlers let livestock roam without fences. Disease, predators and casual hunting have been all that kept feral hog numbers in check in areas where populations persisted. Conservation Department officials estimate the state's feral hog population today at between 5,000 and 10,000.
Even in small numbers, however, feral hogs are bad news. Their habit of rooting for food contributes to soil erosion and reduces plant diversity. They compete for food against native wildlife, such as deer, and they devour the eggs of ground-nesting birds such as quail and turkeys. They can transmit potentially devastating veterinary diseases, such as pseudorabies and brucellosis, not to mention maladies that affect humans, including leptospirosis.
Seeing such problems associated with feral hog populations in other states, the Conservation Department began encouraging hunters to shoot feral hogs on sight as early as 1999. This approach resulted in limited success for a few years; then feral hog numbers began to rise again.
"One of the reasons that hunting didn't work was that hunting alone is not enough," said Private Land Field Program Supervisor Rex Martensen. "Hogs are intelligent animals, and they adapt quickly to being hunted. After a few are killed, the rest become extremely wary, and the effectiveness of hunting drops off sharply."
Another reason hunting alone does not work is the fact that hunting creates an incentive for a few people to ensure hogs' survival. Martensen said the Conservation Department has strong evidence that hogs are being brought into Missouri illegally and released on public land. What else, he asks, could explain the appearance of Eurasian boars in areas previously inhabited only by feral domestic hogs?
Since hunting has not worked, the Conservation Department is adopting a multi-faceted approach similar to that used by state and federal officials in Kansas. It involves traps, sharpshooters and helicopters along with other control methods.
Like sport hunting, trapping is effective only up to a point. Hogs not captured in the first few attempts become trap shy. Some of these trap-savvy animals can be taken at night by sharpshooters using night-vision optics. In some terrain, trap-shy hogs can be taken from the air, using helicopters to locate and pursue them.
The Conservation Department is working with Kansas officials and the USDA Wildlife Services to learn aerial hunting techniques. Training scheduled for later this month on conservation areas in southwest Missouri will get the process started.
"To some people, this might seem like going to extremes," said Martensen, "but the stakes could hardly be higher. Hogs running wild and those brought into Missouri without veterinary health certification could carry diseases capable of devastating the state's agricultural economy. Large-scale livestock operations in other states have been decimated by swine pseudorabies spread by feral hogs."
Another feral hog-transmitted disease, leptospirosis, affects people as well as most animals. Its flu-like symptoms make leptospirosis hard to diagnose. Antibiotics cure most human cases, but about one person in 10 develops a form of Weil's disease, which can be fatal.
Domestic animals can contract leptospirosis from ponds or other water that is contaminated by infected animals. The disease settles in the kidneys and can cause abortions and stillbirths.
Swine brucellosis has been found in wild hogs in Missouri and other states. The human form of brucellosis, undulant fever, causes recurring fever, fatigue and joint pain.
The Conservation Department owns or manages only about 1.7 percent of Missouri's total acreage, so eradicating feral hogs on conservation areas is not a solution to the problem.
"Getting rid of feral hogs on department land is the responsible thing to do to protect those areas and Missouri's livestock industry," said Martensen. "But the really important thing about this program is to show that it can be done and how. If we can do it, there are plenty of folks ready to join us and do their share."
Martensen said potential partners in the Conservation Department's feral hog-eradication effort include other government agencies, nongovernmental conservation organizations and livestock producers.
The Missouri Department of Agriculture and the Missouri Farm Bureau Federation have supported past Conservation Department efforts to eradicate feral hogs.
"Everyone in Missouri has a stake in getting a handle on this problem now, before it becomes a crisis," said Martensen.